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SMPTE 292, originally SMPTE 292M, is a digital video transmission line standard published by the Society of Motion Picture and Television Engineers (SMPTE). This technical standard is usually referred to as HD-SDI; it is part of a family of standards that define a serial digital interface based on a coaxial cable, intended to be used for transport of uncompressed digital video and audio in a television studio environment.

SMPTE 292 expands upon SMPTE 259 and SMPTE 344 allowing for bit-rates of 1.485 Gbit/s, and 1.485/1.001 Gbit/s. These bit-rates are sufficient for and often used to transfer uncompressed high-definition video.[1]

Nomenclature

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The "M" designator was originally introduced to signify metric dimensions. It is no longer used in listings or filenames. Units of the International System of Units (SI) are the preferred units of measurement in all SMPTE Engineering Documents.[2]

Technical details

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The SMPTE 292 standard is a nominally 1.5 Gbit/s interface. Two exact bitrates are defined; 1.485 Gbit/s, and 1.485/1.001 Gbit/s. The factor of 1/1.001 is provided to allow SMPTE 292 to support video formats with frame rates of 59.94 Hz, 29.97 Hz, and 23.98 Hz, in order to be upwards compatible with existing NTSC systems. The 1.485 Gbit/s version of the standard supports other frame rates in widespread use, including 60 Hz, 50 Hz, 30 Hz, 25 Hz, and 24 Hz.

The standard also defines nominal bitrates of 3 Gbit/s, for 50/60 frame per second 1080p applications. This version of the interface is not used (and has not been commercially implemented); instead, either a dual-link extension of SMPTE 292M known as SMPTE 372 or a version running twice as fast known as SMPTE 424 is used for e.g. 1080p60 applications.

Electrical interface

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Originally, both electrical and optical interfaces were defined by SMPTE, over concerns that an electrical interface at that bitrate would be expensive or unreliable, and that an optical interface would be necessary. Such fears have not been realized, and the optical interfaces are seldom if ever used, and are likely to be deprecated in future revisions of the standard.

The cabling used for the SMPTE 292 electrical interface is coaxial cable with a nominal impedance of 75 Ω. Data is encoded in NRZ format, and a linear feedback shift register is used to scramble the data to reduce the likelihood that long strings of zeroes or ones will be present on the interface. The interface is self-clocking. Framing is done by detection of a special synchronization pattern, which appears on the (unscrambled) serial digital signal to be a sequence of twenty ones followed by forty zeroes; this bit pattern is not legal anywhere else within the data payload.

The SMPTE 292 digital interface is known to be reliable (without use of repeaters) at cable lengths of 100 m or greater.

Data format

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The corresponding parallel data formats, defined by SMPTE 274, SMPTE 296, and several other standards, are 20-bit standards; thus SMPTE 292M uses a 20-bit word size. Each 20-bit word consists of two 10-bit datums, coming from two logical (and parallel) data channels, one ("Y") which encodes luminance video samples, the other ("C") which encodes chrominance information. The C channel is further time-multiplexed into two half-bandwidth channels, known as Cr (the "red color difference" channel), and Cb (the "blue color difference" channel). The nominal datarate of the Y channel is 75 Mwords/sec (1.5 Gbit/s divided by 20), and the nominal datarate of each of the two chroma channels is 37.5 Mwords/sec.

Video payload (as well as ancillary data payload) may use any 10-bit word in the range 4 to 1019 (004 to 3FB in hexadecimal) inclusive; the values 0-3 and 1020-1023 (3FC - 3FF) are reserved and may not appear anywhere in the payload. These reserved words have two purposes, for synchronization packets, and for ancillary data headers.

Synchronization packets

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A synchronization packet occurs immediately before the first active sample on every line, and immediately after the last active sample (and before the start of the horizontal blanking region). The synchronization packet consists of four 10-bit words. The first three words are always the same—0x3FF, 0, 0; the fourth consists of 3 flag bits, along with an error correcting code. As a result, there are 8 different synchronization packets possible.

Synchronization packets must occur simultaneously in both the Y and C datastreams.

The flags bits found in the fourth word are known as H, F, and V. The H bit indicates the start of horizontal blank; and synchronization bits immediately preceding the horizontal blanking region must have H set to one. Such packets are commonly referred to as End of Active Video, or EAV packets. Likewise, the packet appearing immediately before the start of the active video has H set to 0; this is the Start of Active Video or SAV packet.

Likewise, The V bit is used to indicate the start of the vertical blanking region; an EAV packet with V=1 indicates the following line (lines are deemed to start EAV) is part of the vertical interval, an EAV packet with V=0 indicates the following line is part of the active picture.

The F bit is used in interlaced and progressive segmented frame formats to indicate whether the line comes from the first or second field (or segment). In progressive scan formats, the F bit is always set to zero.

Other than the fact that synchronization packets occur in parallel in two datastreams (Y and C), their behavior is virtually identical to the packet types defined in CCIR 601 and SMPTE 259, the digital interface commonly used for SDTV.

Line counter and CRC

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To provide additional robustness, the four samples immediately following the EAV packets (but not the SAV packets) contain a cyclic redundancy check field, and a line count indicator. The CRC field provides a CRC of the preceding line (CRCs are computed independently for the Y and C streams), and can be used to detect bit errors in the interface. The line count field indicates the line number of the current line.

Ancillary data

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Like SMPTE 259, SMPTE 292 supports the SMPTE 291 standard for ancillary data. Ancillary data is provided as a standardized transport for non-video payload within a serial digital signal; it is used for things such as embedded audio, closed captions, timecode, and other sorts of metadata. Ancillary data is indicated by a 3-word packet consisting of 0, 3FF, 3FF (the opposite of the synchronization packet header), followed by a two-word identification code, a data count word (indicating 0 - 255 words of payload), the actual payload, and a one-word checksum. Other than in their use in the header, the codes prohibited to video payload are also prohibited to ancillary data payload.

Video payload

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Within the active portion of the video, the data words correspond to signal levels of the respective video components. The luminance (Y) channel is defined such that a signal level of 0 mV is assigned the codeword 64 (40 hex), and 700 millivolts (full scale) is assigned the codeword 940 (3AC) . For the chroma channels, 0 mV is assigned the code word 512 (200 hex), -350mV is assigned a code word of 64 (0x40), and +350mV is assigned a code word of 960 (3C0). Note that the scaling of the luma and chroma channels is not identical. The minimum and maximum of these ranges represent the preferred signal limits, though the video payload may venture outside these ranges (providing that the reserved code words of 0 - 3 and 1020 - 1023 are never used for video payload).

For portions of the vertical and horizontal blanking regions which are not used for ancillary data, it is recommended that the luma samples be assigned the code word 64 (40 hex), and the chroma samples be assigned 512 (200 hex); both of which correspond to 0 mV. It is permissible to encode analog vertical interval information (such as vertical interval timecode or vertical interval test signals) without breaking the interface, but such usage is nonstandard (and ancillary data is the preferred means for transmitting metadata). Conversion of analog sync and burst signals into digital, however, is not recommended—and neither is necessary in the digital interface.

Emmy award

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On July 31, 2013 it was announced that SMPTE won a Technology & Engineering Emmy Award for 2013 by the National Academy of Television Arts and Sciences. The honor recognized the society’s work on development, standardization, and productization of SMPTE 292.[1]

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  • Society of Motion Picture and Television Engineers: SMPTE 274M-2005: Image Sample Structure, Digital Representation and Digital Timing Reference Sequences for Multiple Picture Rates
  • Society of Motion Picture and Television Engineers: SMPTE 292M-1998: Bit-Serial Digital Interface for High Definition Television
  • Society of Motion Picture and Television Engineers: SMPTE 291M-1998: Ancillary Data Packet and Space Formatting
  • Society of Motion Picture and Television Engineers: SMPTE 372M-2002: Dual Link 292M Interface for 1920 x 1080 Picture Raster

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

SMPTE 292

View on Grokipedia
from Grokipedia
SMPTE ST 292-1 is a standard published by the Society of Motion Picture and Television Engineers (SMPTE) that defines the bit-serial and interface specifications for a nominal 1.5 Gbit/s signal/data serial interface, commonly known as HD-SDI, to carry high-definition digital signals. The standard supports two precise bit rates of 1.485 Gbit/s and 1.485/1.001 Gbit/s, with the latter accommodating frame rates derived from standards such as 59.94 Hz, 29.97 Hz, and 23.98 Hz. It serializes parallel source format data, including video, embedded audio, and ancillary data, into a single serial bit stream for transmission over coaxial cables up to 100 meters in length. Originally published as SMPTE 292M in 1998, the standard was revised multiple times, with the current edition (ST 292-1:2018) incorporating updates for expanded applications while maintaining compatibility with earlier versions. It supports key high-definition formats defined in related SMPTE standards, including 1280×720 progressive scan (per SMPTE ST 296) and 1920×1080 interlaced or progressive scan (per SMPTE ST 274), typically in 10-bit 4:2:2 YCbCr color space. These formats enable uncompressed transmission of HD video at frame rates up to 60 Hz (or 59.94 Hz), making it suitable for professional applications. In and , SMPTE ST 292-1 serves as the foundational interface for HD-SDI infrastructure, facilitating the transport of high-definition signals between cameras, switchers, routers, and monitors in studios, mobile units, and transmission chains. Extensions such as dual-link HD-SDI (SMPTE ST 372) enable support for , 12-bit depths, and higher frame rates like 1080p60, enhancing utility in advanced workflows while the standard paves the way for higher-speed successors like 3G-SDI (SMPTE ST 424). The standard's electrical specifications, including and requirements, ensure robust in environments, with optional fiber-optic extensions for longer distances.

Overview

Definition and purpose

SMPTE ST 292-1:2018 defines a bit-serial digital interface for (HDTV) signals, operating at nominal data rates of 1.485 Gbit/s and 1.485/1.001 Gbit/s. This standard specifies the data structure and transmission protocol to support uncompressed HD video over serial links in professional settings. The primary purpose of SMPTE ST 292-1:2018 is to facilitate the point-to-point transmission of high-quality, uncompressed signals, such as /60 and /60 formats, within broadcast production environments using , with practical extensions to fiber-optic media for longer distances. It ensures among equipment by standardizing the serial interface for HD content, enabling seamless integration in workflows from cameras to switchers and systems. The scope encompasses signals employing and Y'CbCr color encoding as defined by BT.709, providing a balance of bandwidth efficiency and visual fidelity for HD production. Additionally, it includes provisions for transport, such as embedded audio channels, timecode, and metadata, formatted according to SMPTE ST 291-1 to accompany the video without compromising the main . Supported video formats include 1920×1080 interlaced and progressive scan at frame rates of 23.98 Hz, 24 Hz, 25 Hz, 29.97 Hz, and 30 Hz, as well as 1280×720 progressive scan at 50 Hz, 59.94 Hz, and 60 Hz, all typically in a 16:9 aspect ratio. These formats align with common HDTV production needs, from film-originated content to broadcast standards. As an evolution within the Serial Digital Interface (SDI) family from lower-rate standards like SD-SDI, it extends capabilities to HD resolutions while maintaining compatibility principles.

Historical development

SMPTE 292M was initially published in October 1998 by the Society of Motion Picture and Television Engineers (SMPTE) to define a bit-serial digital interface for high-definition television systems. This standard emerged in the late 1990s during the industry's shift from analog to digital high-definition broadcasting, extending the foundational serial digital interface (SDI) concepts originally developed for standard-definition video under SMPTE 259M. The development addressed the growing need for reliable, uncompressed transmission of HD signals in production environments, aligning with international efforts to standardize HD studio interfaces. Key revisions followed to refine and expand the standard's applicability. In November 2006, an update provided clarifications on signal specifications and interface requirements. This was succeeded by the February 2008 edition, which further stabilized the electrical and data mapping aspects for broader implementation. By 2012, the standard was redesignated as SMPTE ST 292-1:2012, incorporating provisions for standards such as SMPTE ST 291 to enhance data embedding capabilities within the HD serial interface. The standard was further revised in 2018 as SMPTE ST 292-1:2018, incorporating updates for expanded applications while maintaining compatibility with earlier versions. Adoption accelerated in the early as production became mainstream, with SMPTE 292 enabling efficient signal distribution in studios and broadcast facilities worldwide. Its integration with ITU-R BT.1120 recommendations for HD interfaces further facilitated global interoperability and hastened the transition to digital HD workflows.

Nomenclature and terminology

Standard designations

The standard was originally designated SMPTE 292M upon its publication in 1998, with the "M" suffix denoting approval by the SMPTE standards committee as an engineering document establishing specifications for interchange. This evolved into SMPTE ST 292-1:2012, where "ST" signifies a SMPTE and the "-1" denotes the primary part covering the core signal/data serial interface. The standard was further revised as SMPTE ST 292-1:2018, incorporating updates while maintaining . The standard aligns with relevant recommendations, such as BT.1120 for high-definition digital interfaces. The original SMPTE 292M was withdrawn in 2012 following the publication of ST 292-1, which superseded it to incorporate updates and conform to SMPTE's revised .

Key terms and abbreviations

HD-SDI (High-Definition ) refers to the common implementation of the SMPTE ST 292 standard, which defines a 1.485 Gbps bit-serial interface for transmitting high-definition signals, along with embedded audio and , over or fiber-optic cables. TRS (Timing Reference Signal) denotes the synchronization packets used in SMPTE ST 292 to delineate video timing, specifically comprising the Start of Active Video (SAV) and End of Active Video (EAV) sequences that mark the boundaries of active video lines. SAV (Start of Active Video) is a four-word timing packet in SMPTE ST 292 that signals the beginning of the active video portion within each line, enabling deserializers to align with the video data stream. EAV (End of Active Video) is a corresponding four-word timing packet in SMPTE ST 292 that indicates the conclusion of active video data for a line, followed by line identification and error-checking information. encompasses non-video payloads, such as embedded audio, timecode, or metadata, that are multiplexed into the horizontal and vertical blanking intervals of the SMPTE ST 292 signal, with formatting specified by SMPTE ST 291. CRC (Cyclic Redundancy Check) is an error-detection mechanism employed in SMPTE ST 292 for each video line, generating checksum values for luma and chroma components to verify after the EAV packet. NRZ () describes the binary encoding scheme used in the process of SMPTE ST 292, where logical "1" and "0" states are represented by distinct voltage levels without returning to a baseline between bits, prior to conversion to NRZI for transmission.

Technical specifications

Electrical characteristics

SMPTE 292 defines a nominal of 1.485 Gbit/s for the electrical interface, precisely 1.485 × 10^9 bits/s to accommodate formats such as /60. This rate enables the transmission of uncompressed HDTV signals over while maintaining synchronization for interlaced and formats. The signaling process involves serializing 10-bit parallel data into an NRZ bit stream, followed by bit-level with a self-synchronizing (X^9 + X^4 + 1), and then applying NRZI encoding (using X + 1) for transmission to minimize () and ensure a balanced DC component. This randomizes the data pattern, reducing spectral peaks and improving over long cable runs. The encoded serial data is then transmitted as a continuous bit stream without additional framing at the . For the coaxial interface, the output is single-ended with a nominal voltage level of 800 mV peak-to-peak ±10%, measured differentially across a 75 Ω load to ensure compatibility with (ECL) standards. This amplitude provides sufficient drive for reliable detection while preventing overshoot or undershoot that could degrade eye opening. The signal is AC-coupled to eliminate DC offsets, maintaining a common-mode voltage near ground. The interface specifies a of 75 Ω for the to match requirements and minimize reflections. Connections use BNC connectors compliant with IEC 61169-8, which support the required frequency range up to 1.5 GHz with low . These connectors ensure secure, low-VSWR mating for professional broadcast environments. Transmission distances reach up to 100 meters using high-quality 75 Ω cables such as Belden 1694A, assuming proper equalization at the receiver to compensate for attenuation. specifications include maximum timing of 1.0 UI (10 Hz to 100 kHz bandwidth) at the source and 2.0 UI after 100 m cable, and maximum alignment of 0.2 UI p-p (>100 kHz bandwidth) at the receiver input, accounting for deterministic and random components to ensure margins even after cable-induced dispersion. These tolerances are defined per SMPTE RP 184. Return loss must be ≥15 dB across the frequency range from 5 MHz to 1.485 GHz for both source and load terminations to suppress echoes and maintain signal fidelity. This specification applies to the entire interface, including connectors and cable assemblies, to prevent impedance mismatches that could introduce ghosts or bit errors.

Optical characteristics

The optical interface for SMPTE 292, standardized in SMPTE ST 297, facilitates transmission of the 1.485 Gbit/s signal over fiber optics, providing extended reach beyond limitations while preserving . This interface supports both single-mode and multi-mode fiber, with a typical operating of 1310 nm for single-mode applications to minimize dispersion over longer distances. Transmitter output power is specified in the range of -8 to -12 dBm, enabling reliable short-haul transmission without requiring high-power lasers. Receiver sensitivity is defined at -23 dBm to ensure a (BER) below 10−1210^{-12}, even in the presence of pathological video patterns common in SDI signals. With these parameters, transmission distances extend up to 10 km on single-mode (9/125 µm core) and 300-500 m on multi-mode (50/125 µm or 62.5/125 µm core), depending on and effects. Connector types are duplex LC or SC, ensuring low and compatibility with standard broadcast infrastructure as per SMPTE ST 297 requirements. Jitter performance mirrors the electrical specifications, with deterministic jitter limited to ≤0.2 UI at the receiver output, and the optical eye diagram must exhibit clear opening to support accurate . Additionally, the optical modulation amplitude is required to be at least 7 dB to maintain sufficient signal contrast for error-free detection. The encoding process involves direct conversion from the electrical NRZ scrambled signal to optical, without altering the applied in the SMPTE 292 electrical domain, thus ensuring seamless between optical and electrical segments.

Data structure and mapping

SMPTE ST 292-1 defines the as a continuous serial stream of 10-bit words transmitted at a nominal rate of 1.485 Gbit/s (or 1.485/1.001 Gbit/s), enabling the transport of payloads such as 1280×720 progressive or interlaced/progressive formats. Word alignment is facilitated by distinctive patterns within the Timing Reference Signals (TRS), specifically the sequences 3FFh and 000h embedded in the Start of Active Video (SAV) and End of Active Video (EAV) packets, allowing receivers to synchronize to the 10-bit word boundaries without external clock references. The packets, SAV and EAV, each form a 40-bit sequence consisting of the fixed preamble words 3FFh, 000h, 000h, followed by a variable XYZ word that encodes key timing flags: bit 9 fixed at 1, bit 8 for field identification (F), bit 7 for vertical blanking (V), bit 6 for horizontal position (H=0 for SAV, 1 for EAV), bits 5–2 as bits (typically set to ensure detection reliability), and bits 1–0 at 0. These packets demarcate the boundaries of active video within each line, with SAV preceding the and EAV following it, supporting precise raster timing extraction. Line structure follows the source format specifications, such as SMPTE ST 274 for formats, which allocate 1125 total lines per frame (or 1124 in some variants), encompassing active video lines (e.g., lines 21–1120 for interlaced) and blanking intervals for and timing. Line numbering is provided immediately after each EAV via two 10-bit words, LN0 and LN1, where bits 5–10 of LN0 and bits 4–9 of LN1 form an 11-bit binary line counter (with additional parity and protection bits), enabling receivers to track position within the frame. Ancillary data is embedded within the horizontal ancillary (HANC) and vertical ancillary (VANC) spaces of the blanking intervals, formatted as per SMPTE ST 291-1 using a packet structure that includes header words for word alignment (3FFh, 000h, 000h), a Data Identification (DID) word, a Identification (SDID) word, user data words, and optional checksums. For example, DID value 0x61 paired with specific SDID values (e.g., 0x02 for closed captions) designates VANC packets, allowing multiplexing of metadata like timecode or audio descriptors without impacting the video payload. HANC data is preferentially placed in the C channel during horizontal blanking, while VANC occupies full lines in vertical blanking. The video payload occupies the active line regions, mapped as 10-bit 4:2:2 samples divided into separate Y (luma) and C (chroma) data streams, with the C stream Cb and Cr samples at half the Y sample rate. This results in 20 bits processed per clock cycle (10 bits Y + 10 bits C), supporting active video sample counts such as 1920 per line for 1080 formats or 1280 for 720 formats, within total line lengths of 2200 words (1080) or 1650 words (720) including blanking. Error detection employs line-based Cyclic Redundancy Checks (CRC) for each Y and C stream, implemented as 18-bit values (YCR0/YCR1 and CCR0/CCR1) appended after the line data and line number words, computed over the active line and blanking content excluding TRS and CRC itself. The CRC uses the polynomial x18+x5+x4+1x^{18} + x^5 + x^4 + 1, with an initial value of zero, providing horizontal parity detection; vertical parity across fields is optional via cumulative CRCs. To ensure DC balance and reduce electromagnetic interference, the entire bit-serial stream (post-parallel-to-serial conversion) is scrambled using a linear feedback shift register with the polynomial x9+x4+1x^9 + x^4 + 1, applied self-synchronously without reset.

Applications and impact

Usage in video production

SMPTE 292, defining the HD-SDI interface, serves as a cornerstone for transporting uncompressed high-definition video in professional video production workflows, particularly in live broadcasting where it enables real-time transmission from cameras to production switchers in studio environments. In post-production, it facilitates the movement of HD footage between editing suites, color grading stations, and storage systems, ensuring low-latency, high-fidelity signal integrity essential for collaborative editing processes. Camera-to-switcher links in HD studios commonly rely on SMPTE 292 for seamless integration during live events, such as sports broadcasts or news productions, where multiple sources must be switched rapidly without signal degradation. Integration of SMPTE 292 occurs across diverse ecosystems, including video servers for playback and recording, production switchers for mixing inputs, and monitors equipped with HD-SDI inputs for precise viewing. These components, often from manufacturers like Grass Valley or , support embedded audio and within the HD-SDI stream, streamlining workflows by reducing the need for separate cabling. For cable infrastructure, typical setups employ RG-6 cables or Belden 1694A, which maintain signal quality over distances up to 100 meters, with cable equalizers deployed to compensate for in longer runs and preserve timing accuracy. To extend capabilities beyond standard 4:2:2 color sampling or frame rates, multi-link configurations using dual-link HD-SDI as specified in SMPTE 372M combine two SMPTE 292 links, enabling support for RGB color depths or higher frame rates like at 60 fps by distributing data across parallel cables. In modern hybrid environments, SMPTE 292 plays a transitional role alongside IP-based systems, bridging legacy SDI gear with emerging networks before full adoption of SMPTE ST 2110 for over IP, allowing facilities to incrementally upgrade without overhauling infrastructure. Challenges in these deployments include managing accumulation over extended cable runs, which can distort timing and lead to artifacts; reclockers are routinely incorporated to regenerate the , filtering and restoring compliance with SMPTE 292 parameters for reliable operation.

Awards and industry recognition

In 2013, the Society of Motion Picture and Television Engineers (SMPTE) received the Technology & Engineering Emmy Award from the National Academy of Television Arts and Sciences for its development of the HD-SDI standard defined in SMPTE 292, recognizing its foundational role in high-definition digital video transmission. The award was announced on July 31, 2013, highlighting how the standard established a reliable that supported uncompressed HD video and embedded audio, enabling seamless integration across broadcast . SMPTE 292 played a pivotal role in the global shift to digital high-definition during the , standardizing HDTV transmission formats and facilitating the replacement of analog systems with more efficient digital workflows. By providing a consistent 1.5 Gbps interface for formats like and , it reduced signal degradation issues inherent in analog transmission and supported the widespread adoption of HD in professional production environments. This standardization lowered operational complexities and costs associated with legacy analog infrastructure, accelerating the industry's transition to digital HD. As a of modern video , SMPTE 292 laid the groundwork for subsequent high-speed interfaces and remains integral to broadcast HD infrastructure, influencing the majority of professional setups by the early . Its legacy extends to international standards, with contributions to recommendations such as BT.1120, which references SMPTE 292 for HDTV studio signal interfaces. Additionally, the standard has seen broad adoption in major film and television productions, including Olympic broadcasts, where it has been used for HD-SDI signal production in events like the 2020 and Beijing 2022 Games.

Predecessor standards

SMPTE ST 259:2008, also known as SD-SDI, defines a 10-bit operating at bit rates of 143 Mb/s, 177 Mb/s, 270 Mb/s, and 360 Mb/s, primarily for transmitting uncompressed (SDTV) signals in (NTSC) or 625-line (PAL) formats using 4:2:2 component sampling or 4fsc composite digital signals. Originally published in 1989 as SMPTE 259M and revised in 2008, this standard established the foundational serial transmission format for but lacked mappings for high-definition payloads, focusing instead on lower-bandwidth SD resolutions. SMPTE 292 directly built upon ST 259 by scaling its core serial interface elements—such as (NRZ) encoding with scrambling to minimize and ensure reliable transmission, along with time reference signal (TRS) structures for —to accommodate higher bit rates suitable for HD video. This adaptation preserved compatibility with existing SDI infrastructure while extending capabilities to HD formats, marking a key evolutionary step in serial digital interfaces. Another significant precursor was SMPTE 125M (1995), which specified a bit-parallel digital interface for signals in 4:2:2 and 4:4:4 color spaces, supporting 525/625-line HD systems and serving as a bridge from parallel to serial transmission methods in subsequent standards like SMPTE 292.

Successor and complementary standards

SMPTE ST 424:2006, commonly known as 3G-SDI, extends the capabilities of SMPTE 292 by defining a 2.970 Gbit/s serial digital interface to support higher frame rates and resolutions such as /60 or 2K formats, utilizing either dual-link configurations from the 1.485 Gbit/s HD-SDI or a single 3 Gbit/s electrical path. This standard maintains compatibility with existing coaxial cabling while doubling the data rate to accommodate video and deeper color depths beyond the limitations of SMPTE 292's 1.485 Gbit/s bitrate. Building further on this progression, SMPTE ST 2081:2015 introduces 6G-SDI with a 5.94 Gbit/s interface, enabling transmission of 4K/UHD (2160p) signals at up to 30 fps in single-link mode or higher rates via quad-link configurations, thus addressing the bandwidth demands of ultra-high-definition production that exceed SMPTE 292's capacity for HD workflows. The standard specifies mappings for 2160-line source images and across single, dual, or quad links, ensuring seamless integration with prior SDI infrastructure while scaling for 4K resolutions. Extending this further, SMPTE ST 2082-10:2015 defines 12G-SDI with an 11.88 Gbit/s interface, supporting transmission of 4K/UHD (2160p) signals at up to 60 fps in single-link mode, along with mappings for and compatibility with existing infrastructure. Complementary to these serial extensions, SMPTE ST 372:2009 defines a dual-link HD-SDI interface operating at 1.485 Gbit/s per link (totaling 2.97 Gbit/s), specifically for transporting RGB 10-bit or 12-bit formats at or 2048 × 1080 resolutions, which enhances color fidelity in environments building on SMPTE 292's foundational structure. Additionally, SMPTE ST 2110 provides a packetized media framework over IP networks, separating video, audio, and streams for real-time transport, serving as a modern alternative to cable-based SDI standards like SMPTE 292 by enabling flexible, scalable distribution in IP-centric broadcast facilities. While SMPTE 292 continues to underpin legacy high-definition systems due to its established reliability in /p applications, these successors and complements evolve the ecosystem toward 4K and beyond through increased bit rates, multi-link options, and IP packetization, facilitating the transition to higher-resolution and networked .

References

  1. https://standards.globalspec.com/std/10382250/smpte-st-292-1
  2. https://docs.amd.com/r/en-US/xapp1248-smpte-sdi-ultrascale-gth-transceivers/Glossary
  3. https://tech.ebu.ch/docs/techreports/tr002.pdf
  4. https://tech.ebu.ch/files/live/sites/tech/files/shared/tech/tech3375.pdf
  5. https://store.accuristech.com/standards/smpte-st-292-1
  6. https://www.intertekinform.com/en-us/standards/smpte-st-292-1-2012-1037752_saig_smpte_smpte_2421602/
  7. https://download.tek.com/document/25W-15960-6.pdf
  8. https://bullfrog-sunfish-plmw.squarespace.com/s/SDI-SMPTE-Primer.pdf
  9. https://standards.globalspec.com/std/1087346/smpte-292
  10. https://www.smpte.org/blog/sdi-ip-evolution-distribution
  11. https://www.itu.int/rec/R-REC-BT.1120/en
  12. https://store.accuristech.com/standards/smpte-292m
  13. https://www.techtarget.com/searchnetworking/definition/Serial-Digital-Interface
  14. https://www.intertekinform.com/en-gb/standards/smpte-st-292-1-2012-1037752_saig_smpte_smpte_2421602/
  15. https://www.intertekinform.com/en-gb/standards/smpte-st-292-1-2018-1037752_saig_smpte_smpte_2621362/
  16. https://www.smpte.org/standards/document-index/st
  17. https://www.telestream.net/pdfs/technical/Guide-to-Standard-HD-Digital-Video-Measurements-25W147006.pdf
  18. https://www.ti.com/lit/gpn/LMH0030
  19. https://www.analog.com/media/en/technical-documentation/data-sheets/MAX3812.pdf
  20. https://evertz.com/resources/manuals/?id=373
  21. https://evertz.com/resources/manuals/?id=64
  22. https://www.technohouse.co.jp/wp/wp-content/uploads/2018/07/evertz_7707OE-3G-1_180709.pdf
  23. https://www.markertek.com/Attachments/Specifications/Canare/L-2.5CFB300MBLACK-Specifications.pdf
  24. https://www.ti.com/lit/pdf/snla178
  25. https://www.optoway.com/upload/files/SFP/SPS-7110V-1TG.pdf
  26. https://www.tautec-electronics.de/Datenblaetter/Schaltkreise/GO2920.pdf
  27. https://www.gigalight.com/downloads/datasheets/optical-transceivers/sfpp/sdi/GHP-316G-L2CD.pdf
  28. https://www.thinklogical.com/wp-content/uploads/2018/01/SDI-Xtreme-3G.pdf
  29. https://tech.ebu.ch/docs/tech/tech3299.pdf
  30. https://www.tvtechnology.com/news/the-1485gbs-hdtv-sdi-interface
  31. https://datatracker.ietf.org/doc/rfc3497/
  32. https://www.farnell.com/datasheets/1500522.pdf
  33. https://ww1.microchip.com/downloads/aemdocuments/documents/fpga/productdocuments/userguides/ip_cores/directcores/coresditx_hb.pdf
  34. https://www.samimgroup.com/blog/serial-digital-interface-video/
  35. https://www.optcore.net/introduction-to-sdi/
  36. https://www.belden.com/products/cable/video-cable/coaxial-video-cable/1694a
  37. https://www.extron.com/download/files/articles/hdsdihdmi_ts.pdf
  38. https://www.harmonicinc.com/insights/blog/all-ip-or-hybrid-sdi/
  39. https://telvue.com/clarifying-sdi/
  40. https://www.tvtechnology.com/news/smpte-to-receive-tech-emmy-for-hdsdi-standard
  41. https://plsn.com/newsroom/projection-connection/smpte-to-receive-emmy-award-for-hd-sdi-standard/
  42. https://blog.semtech.com/sdi-is-dead-long-live-sdi
  43. https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BT.2246-7-2020-PDF-E.pdf
  44. https://www.sportsvideo.org/2021/07/27/live-from-tokyo-olympics-obs-technical-area-offers-inside-look-at-how-the-games-come-together/
  45. https://reference.globalspec.com/standard/11004441/st-259-2008
  46. https://www.intertekinform.com/en-gb/standards/smpte-st-259-2008-1038000_saig_smpte_smpte_2422098/
  47. https://www.thebroadcastbridge.com/content/entry/15013/advances-in-12g-sdi-part-1-developing-12g-sdi
  48. https://wiki.millersville.edu/download/attachments/37946381/25W_14700_0A.pdf?version=1&modificationDate=1394462562000&api=v2
  49. https://www.ti.com/lit/pdf/snla171
  50. https://store.accuristech.com/standards/smpte-st-424?product_id=2826891
  51. https://www.sony.ca/en/electronics/support/business-professional-broadcast-production/articles/00236240
  52. https://www.intertekinform.com/en-gb/standards/smpte-st-2081-1-2015-amd-1-2016-1037851_saig_smpte_smpte_2421800/
  53. https://store.accuristech.com/standards/smpte-st-2082-1
  54. https://store.accuristech.com/standards/smpte-st-372?product_id=2782466
  55. https://www.smpte.org/standards/st2110
  56. https://www.smpte.org/smpte-st-2110-faq
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